Process for manufacturing retroreflective printed material

ABSTRACT

A process for manufacturing retroreflective printed material, the process comprising a) providing a composite comprising a temporary support sheet with a layer of microspheres partially embedded in the temporary support sheet such that the surfaces of the microspheres are partially exposed; b) applying a reflecting layer on the microspheres; c) applying a priming layer either on the partially exposed surfaces of the microspheres or on the reflecting layer; d) transferring a printed design layer from a transfer medium with the printed design on the primer layer and separating the transfer medium without the printed design from the printed design layer; e) applying a binder layer on the printed design layer; f) applying a base fabric on the binder layer and separating the temporary support sheet from the layer of microspheres, thereby creating the retroreflective printed material. A retroreflective printed material made according to the process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase filing of International PatentApplication No. PCT/EP2003/012948 entitled “Process for ManufacturingRetroreflective Printed Material,” filed Nov. 19, 2003, which claimspriority from European Patent Application No. 02425785.9 filed Dec. 19,2002; the contents of which are incorporated by reference herein intheir entirety.

FIELD

The present invention is related to a process for manufacturingretroreflective printed material.

BACKGROUND

The use of safety garments comprising retroreflective printing reducesthe risk of accidents, especially for persons in certain professionssuch as for example firefighters and paramedics, as well as forathletes. Commercial products suitable for use with reflective garmentsgenerally consist of a single color. For example, U.S. Pat. No.4,763,985 to Bingham, U.S. Pat. No. 5,283,101 to Li and U.S. Pat. No.5,738,746 to Billingsley et al., disclose launderable retroreflectivegrey-colored products.

A number of patents disclose processes for producing colored effects andprinted effects, as well as reflectivity. For example, U.S. Pat. No.5,962,121 to Mori discloses a retroreflective structure capable ofexhibiting a decorative rainbow-colored effect during both daytime andnighttime. U.S. Pat. No. 4,605,461 to Ogi discloses a process fortransferring a retroreflective pattern onto a fabric. U.S. Pat. No.4,102,562 to Harper et al. discloses retroreflective images formed ongarments and other substrates. U.S. Pat. No. 5,508,105 to Orensteen etal. discloses a thermal printing system and a colorant/binder forprinting frangible, retroreflective sheeting material. U.S. Pat. No.5,620,613 to Olsen discloses the printing of designs or emblems ongarments, where the design comprises a monolayer of microspheres, and afirst printing of a first color layer with a silk-screening system. Whenthe prints of the first color are dried, subsequent colors can beprinted through the same technique until the design on the layer ofmicrospheres is completed. A similar patent for decorating textilesurfaces, U.S. Pat. No. 5,679,198 to Olsen et al., discloses amulti-step printing of many colors prepared with a polyester resin andan isocyanate hardener, dried before printing the following color. Alsoin U.S. Pat. No. 5,785,790 to Olsen et al., the same silk-screeningmulti-color printing technique is used with a system of colors made ofpolyester resin hardened with isocyanate. Many other United Statespatents disclose processes for producing retroreflective materials,including U.S. Pat. No. 2,231,139 to Reininger, U.S. Pat. No. 2,422,256to Phillippi, U.S. Pat. No. 3,689,346 to Rowland, U.S. Pat. No.4,082,426 to Brown, U.S. Pat. No. 4,656,072 to Coburn, Jr. et al., U.S.Pat. No. 4,952,023 to Bradshaw et al. and U.S. Pat. No. 5,643,400 toBernard et al. U.S. Pat. No. 6,120,636 to Nilsen et al. discloses a highspeed, low cost process for producing sheets patterned with drawings andemblems using a rotary screen printing system with cylinders, andhardening with UV lamps.

There does not appear, however, to be a practical process for producinga printed retroreflective product for fashion garments using designscontaining one or more than one color. While, processes usingsilk-screen printing with one water-based color or solvent-based colorshave been proposed, these processes are unfeasible for reproducingfashion designs with many colors upon a retroreflective material.

Additionally, many patents disclose the use of screen-printingtechnology, such as for example U.S. Pat. No. 5,620,630 to Onishi et al.and U.S. Pat. No. 5,785,790 to Olsen et al., among others. With thisscreen-printing technology, however, it is impossible to print designson garments comprising many colors while maintaining design and coloraccuracy on a layer of microspheres to produce retroreflectingmaterials. The same is true of a rotary screen-printing system disclosedin U.S. Pat. No. 6,120,636 to Nilsen et al.

Therefore, there remains a need for a process for printingretroreflecting products comprising one or more than one color, with ahigh production speed, production flexibility and without producingsignificant amounts of pollution.

SUMMARY

According to one embodiment of the present invention, there is provideda process for manufacturing retroreflective printed material, theprocess comprising a) providing a composite comprising a temporarysupport sheet with a layer of microspheres partially embedded in thetemporary support sheet such that the surfaces of the microspheres arepartially exposed; b) applying a reflecting layer on the microspheres;c) applying a priming layer either on the partially exposed surfaces ofthe microspheres or on the reflecting layer; d) transferring a printeddesign layer from a transfer medium with the printed design on theprimer layer and separating the transfer medium without the printeddesign from the printed design layer; e) applying a binder layer on theprinted design layer; f) applying a base fabric on the binder layer andseparating the temporary support sheet from the layer of microspheres,thereby creating the retroreflective printed material, where thereflecting layer is either applied on the microsphere surface of thecomposite between the priming layer and the microsphere surface of thecomposite, or is applied on the printed design layer between the printeddesign layer and the binder layer. In one embodiment, the microspheresare transparent glass microspheres. In another embodiment, themicrospheres have a diameter, and the microspheres are partiallyembedded in the temporary support sheet to a depth ranging between 40%and 50% of the microsphere diameter.

In another embodiment, the temporary support sheet comprises a coatingfilm and a backing sheet. In a preferred embodiment, the coating film isselected from the group consisting of a polymeric coating film,polyethylene, polypropylene, a low-density polyethylene thermo-adhesivefilm and an acrylic auto-adhesive film. In a preferred embodiment, thebacking sheet is selected from the group consisting of kraft paper andpolyester film. In a preferred embodiment, providing a compositecomprises placing the microspheres on the temporary support sheet by aprocess selected from the group consisting of printing, cascading,transferring and screening.

In another embodiment, the reflecting layer is a dielectric mirror layerapplied on the microsphere surface of the composite, and where thepriming layer is applied on the dielectric mirror layer. In anotherembodiment, the reflecting layer is a light reflecting material layerapplied on the printed design layer, and where the binder layer isapplied on the light reflecting material layer. In a preferredembodiment, the light reflecting material layer is a vapor coating of ametal or thin reflective aluminum film layer applied by vacuumdeposition.

In one embodiment, the priming layer is selected from the groupconsisting of a thin layer of transparent thermo-adhesive bicomponentpolyurethane resin and a resin of a water polyether polyurethanedispersion. In another embodiment, the printed design layer from atransfer medium with the printed design comprises a plurality of colors.In another embodiment, the transfer medium with the printed designcomprises a design with sublimate pigments. In a preferred embodiment,transferring a printed design comprises thermo-transferring at atemperature between 180° C. and 220° C.

In another embodiment, the transfer medium with the printed designcomprises a design printed on a polymer film. In a preferred embodiment,transferring a printed design comprises thermo-transferring at atemperature between 100° C. and 120° C.

In one embodiment, the binder layer is selected from the groupconsisting of a bicomponent polyurethane resin and a thin layer of ahot-melt adhesive.

According to another embodiment of the present invention, there isprovided a retroreflective printed material made according to theprocess of the present invention. In one embodiment, there is providedan article of clothing, sportswear or footwear comprising theretroreflective printed material of the present invention.

According to another embodiment of the present invention, there isprovided a retroreflective printed material comprising: a) amicrospheres layer; b) a priming layer on the microsphere layer; c) aprinted design layer on the primer layer; d) a binder layer on theprinted design layer; e) a base fabric on the binder layer; and f) areflecting layer; where the reflecting layer is either between themicrosphere layer and the priming layer, or is between the printeddesign layer and the binder layer. In one embodiment, the microspheresare transparent glass microspheres. In another embodiment, thereflecting layer is a dielectric mirror layer. In one embodiment, thereflecting layer is a vapor coating of a metal or thin reflectivealuminum film layer. In another embodiment, the priming layer isselected from the group consisting of a thin layer of transparentthermo-adhesive bicomponent polyurethane resin and a resin of a waterpolyether polyurethane dispersion. In one embodiment, the printed designlayer comprises a plurality of colors. In another embodiment, the binderlayer is selected from the group consisting of a bicomponentpolyurethane resin and a thin layer of a hot-melt adhesive.

FIGURES

These and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying figures which depict someof the steps in certain embodiments of the process of the presentinvention, where:

FIG. 1 is a partial cross-sectional view of a portion of an article ofclothing that is partially delaminated from the temporary support sheet,according to the present invention;

FIG. 2 is a schematic drawing of a machine that can be used in theprocess of the present invention;

FIG. 3 is a schematic drawing of a machine for transferring printeddesigns with sublimate pigments according to the present invention;

FIG. 4 is a partial cross-sectional view of a composite of a temporarysupport sheet with partially embedded microspheres according to thepresent invention;

FIG. 5 is a schematic plan view of a transfer medium with a printeddesign suitable for use with the present method; and

FIG. 6 is a schematic drawing showing the design on a transfer mediumwith the printed design, as shown in FIG. 5, being transferred to asurface comprising a layer of microspheres as the printed transferredimage, while the transfer medium without the printed design is partiallyreleased from the printed transferred image, according to the presentinvention.

DESCRIPTION

According to one embodiment of the present invention, there is provideda process for manufacturing retroreflective printed material. Theprocess can be performed at a rapid production rate, is flexible anddoes not produce significant amounts of pollution. The machinery usedwith the present process requires a relatively low investment of capitaland a relatively small amount of floor space compared with otherprinting processes, and requires no auxiliary equipment. Moreover,commercial transfer media suitable for use with the present process arewidely available. The present invention can be used to produceretroreflective printing on a substrate, such as for example fabric forgarments. The present process is especially suited for printing complexdesigns in multiple colors on retroreflecting garments for the fashionindustry, such as for example, clothing, sportswear, footwear andfashion accessories, as well as for producing retroreflective printingon products used in high risk professions where high visibilityincreases safety. The present process involves transferring a printeddesign comprising one or more than one color on a paper or plastic baseonto the surface of a temporary support sheet having a layer ofpartially embedded microspheres and coated with a priming layer.

Though certain steps of the process are disclosed and shown in theFigures, the steps are not intended to be limiting nor are they intendedto indicate that each step depicted is essential to the process, butinstead are exemplary steps only. Further, though the present inventionis disclosed in part with reference to certain examples, which show someof the features and advantages of the invention, the ingredients and thespecific amounts of the ingredients disclosed, as well as otherconditions and details are not intended to be limiting to the scope ofthe present invention. Other ingredients, amounts and conditions can beused, as will be understood by those with skill in the art withreference to this disclosure. Certain embodiments of the process willnow be disclosed in detail.

All dimensions specified in this disclosure are by way of example onlyand are not intended to be limiting. Further, the proportions shown inthese Figures are not necessarily to scale. As will be understood bythose with skill in the art with reference to this disclosure, theactual dimensions of any device or part of a device disclosed in thisdisclosure will be determined by its intended use.

Unless otherwise specified, all amounts expressed in the examples are inparts by weight.

According to one embodiment of the present invention, there is provideda process for manufacturing retroreflective printed material. In oneembodiment, the present process comprises, first, providing a compositeof a temporary support sheet comprising a layer of microspherespartially embedded in the temporary support sheet such that the surfaceof the microspheres are partially exposed. In a preferred embodiment,the microspheres are transparent glass microspheres. In anotherpreferred embodiment, the temporary support sheet comprises a layer ofsoftened polymer, and the microspheres partially embedded in thesoftened polymer to a depth ranging between 20% and 50% of themicrosphere diameter, as conventionally used in retroreflectivematerials, and as disclosed in U.S. Pat. No. 3,700,305 to Bingham andU.S. Pat. No. 6,416,188 B1 to Shusta et al. among other sources. Next, adesign from a commercial transfer medium is thermo-transferred onto themicrosphere surface of the composite.

Two kinds of commercial transfer media with a printed design can be usedwith the present method: 1) designs with sublimate pigments printed on apaper base; and 2) designs printed on a polymer film supported by arelease paper base or a polymer film base, such as for examplepolypropylene film. When thermo-transferring a design with sublimatepigments, the transfer temperature ranges between 180° C. and 220° C. Atransfer temperature close to 220° C. causes a maximum yield of colortransfer, but a partial transfer of colors at lower temperatures canalso give a satisfactory aesthetic design on the final retroreflectiveprinted product.

When thermo-transferring a design printed on polymer film, the presentprocess comprises applying a priming layer on the microsphere surface ofthe composite. In one embodiment, the priming layer is as a thin layerof transparent thermo-adhesive bicomponent polyurethane resin having athickness of about 1 micron. The priming layer is partially cured bydrying, and operates as thermo-adhesive between microspheres and thedesign printed on the polymer film. In this embodiment, the transfertemperature is lower than 150° C. In a preferred embodiment, thetransfer temperature is between 100° C. and 120° C.

The present process further comprises applying a reflecting layerapplied on the partially exposed surfaces of the microspheres. In oneembodiment, the reflecting layer comprises a substantially transparentdielectric mirror layer. In another embodiment, the reflecting layercomprises a light reflecting material layer applied on the printeddesign layer over the microsphere surface of the composite. In apreferred embodiment, the light reflecting material layer is a thinreflective aluminum film layer by vacuum deposition after the printingprocess. When the reflective aluminum film layer is applied, thedielectric mirror layer is not necessary as the product produced has asufficient reflective intensity for a printed fashion product without adielectric mirror layer.

In another embodiment, the process further comprises applying a binderlayer on the printed design layer, or on the light reflecting materiallayer if present. The binder layer is partially dried and a base fabricis applied to the binder layer. In one embodiment, the binder layer is abicomponent polyurethane resin. In another embodiment, the binder layeris a thin layer of a hot-melt adhesive.

Referring now to FIG. 4, there is shown a partial cross-sectional viewof a composite of a temporary support sheet with partially embeddedmicrospheres according to the present invention. As can be seen, thetemporary support sheet 20 comprises a coating film 2 and a backingsheet 3. The coating film 2 is a softenable material, such as forexample a polymer. In one embodiment, the coating film 2 is a polymericcoating film. In another embodiment, the coating film 2 is a polymerselected from the group consisting of polyethylene and polypropylene. Ina preferred embodiment, the coating film is a low-density polyethylenethermo-adhesive film. In another embodiment, the polymeric coating filmis an acrylic auto-adhesive film. The backing sheet 3 comprises a stiffmaterial. In one embodiment, the backing sheet is selected from thegroup consisting of kraft paper and polyester film. The temporarysupport sheet 20 can be produced by known processes, such as disclosedin U.S. Pat. No. 4,102,562 to Harper et al.

The microspheres 1 used in the present invention will typically have anaverage diameter in the range of about 30 to 200 microns and arefractive index of between about 1.7 to 2.0. Preferably, themicrospheres 1 are arranged substantially in a monolayer on thetemporary support sheet 20. The microspheres 1 can be placed on thetemporary support sheet 20 by printing, cascading, transferring,screening or any other suitable process, as will be understood by thosewith skill in the art with reference to this disclosure. Afterplacement, the microspheres 1 are embedded in the temporary supportsheet 20 to a depth of between about 20% to 50% of their averagediameter, such as for example using a pressure roller or by heating thesoftened polymer, yielding a composite of the temporary support sheetand microspheres 33.

Referring now to FIG. 1, there is shown a partial cross-sectional viewof a retroreflective printed material 10 being produced according to thepresent invention, as it is partially separated from the temporarysupport sheet 20 part of the composite of a temporary support sheet andmicrospheres 33. As can be seen, in one embodiment, a dielectric mirrorlayer 4 is disposed adjacent to the surface of the microspheres 1.Further, a priming layer 5 covers the microsphere surface of thecomposite 33, or, as shown, the dielectric mirror layer 4 when present.A printed design layer 6 is disposed on the priming layer, andpreferably has a thickness of less than 0.1 micron in the case ofdesigns with sublimate pigments printed on a paper base, and less than0.5 microns in the case of designs having a polymer film supported by arelease paper base or a polymer film base. In one embodiment, theprinted design layer 6 is covered with a light reflecting material layer7, such as for example a vapor coating of a metal, a vacuum-nebulizedreflective aluminum film layer, or other suitable light reflectingmaterial, as will be understood by those with skill in the art withreference to this disclosure. When the light reflecting material layer 7is present, the dielectric mirror layer 4 is not necessary. Finally, abinder layer 8 covers the printed design layer 6, or the lightreflecting material layer 7 when present, and binds a base fabric 9,such as for example a polyester/cotton fabric, a nylon knitted fabricmade of a Lycra® (E.I. du Pont De Nemours and Company, Wilmington, Del.US) or other textile base fabrics.

Referring now to FIG. 2 and FIG. 3, there are shown schematic drawingsof machines that can be used in the process of the present invention. Ascan be seen, the machines comprise a rotary machine 29 for transferprinting using a heated calender, such as for example, a rotary machinemanufactured by Lemaire & Cie, Roubaix, France or Monti OfficineFonderie S.p.A., Thiene, Italy.

FIG. 3 is a schematic drawing of a machine for transferring printeddesigns with sublimate pigments according to the present invention. Ascan be seen, the composite layer 33 supplied by cylinder 40, and thetransfer medium with the printed design 30 supplied by a cylinder 24 arepressed together between a heated cylinder 27 and a felt 26 in acontinuous process. At the end of the process, the machine dispenses thetransfer medium without the printed design 31 wound on a cylinder 25,and the printed transferred image 34 wound on another cylinder 32.

FIG. 2, is a schematic drawing of a continuous machine for doctor-knifecoating the microsphere surface of a composite of a temporary supportsheet and microspheres 33. As can be seen, the continuous printingprocess coats the composite of a temporary support sheet andmicrospheres 33 supplied by a cylinder 40 with a priming layer 5supplied by a cylinder 22 in a coating machine 23. At the end of theprocess, the machine dispenses the printed transferred image 34 wound ona cylinder 28.

Referring now to FIG. 5, there is shown a schematic plan view of atransfer medium with a printed design 30 suitable for use with thepresent method. In this example, the design comprises images derivedfrom natural subjects, and comprises 8 colors labeled a, b, c, d, e, f,g and h. Transfer media with printed designs of this type are widelyavailable commercially, and are widely used in many applications in thetextile industries, as well as in other fields, such as for example, inthe fields of household accessories, furniture, interior decorations,and motor vehicles. Samples of retroreflective printed material wereprepared according to the present invention using transfer media fromTransfertex GmbH & Co., Kleinostheim, Germany and a polypropyleneprinted film (Decotrans™) from Miroglio S.p.A.—Sublitex, Alba, Italy.

Referring now to FIG. 6, there is shown a schematic drawing showing thedesign on a transfer medium with the printed design 30, as shown in FIG.5, being transferred to a surface comprising a layer of microspheres asthe printed transferred image 34, while the transfer medium without theprinted design 31 is partially released from the printed transferredimage 34, according to the present invention.

EXAMPLE 1

A monolayer of glass microspheres having diameters between 40 and 100microns was produced by cascading the microspheres onto a kraft papercovered with an acrylic auto-adhesive film. The layer of microsphereswas then transferred onto a temporary support sheet comprising a backingsheet of polyester covered with a coating film of low-densitypolyethylene thermo-adhesive film 50 microns thick. The transfer wasmade using a heated calender as shown in FIG. 3, at a cylindertemperature of 140° C. The contact time was 5 seconds and the pressurebetween the heated cylinder and the felt was 5 bars, which yielded apenetration of the microspheres into the temporary support sheet ofabout 40% of their diameter, thereby creating a composite of a temporarysupport sheet and microspheres.

A dielectric mirror layer, as described in U.S. Pat. No. 3,700,305 toBingham, was then applied to the exposed surface of the microspheres onthe composite. The amount of the dielectric mirror layer was about 4g/m².

A bicomponent polyurethane resin priming layer was next applied over thedielectric mirror layer, by coating the dielectric mirror layer with thea solution according to formulation 1 with a doctor-knife coatingmachine or a graved-roll coating machine. Formulation 1 IngredientsParts by Weight Polyurethane resin (“B 10” from COIM 100 S.p.A. Milan,Italy) Curing agent (“Imprafix TH” from Bayer 5 Material Science AG,Leverkusen, Germany) Methylethylketone 150

The priming layer was dried and partially cured at 110° C.

At the end of the oven as disclosed with respect to FIG. 2, the productwas fed into the calender, heated to 130° C., and laminated with atransfer medium with the printed design comprising a polypropyleneprinted film (Decotrans™) having the design shown in FIG. 5. The contacttime was about 10 seconds. Then, the polypropylene portion of thetransfer medium without the printed design and the printed transferredimage were separated. Next, a binder layer comprising a solution ofpolyurethane resin according to formulation 2, was applied to theprinted transferred image at a thickness of approximately 125 micronswhen wet. Formulation 2 Ingredients Parts by Weight Polyurethane resin(“B 10” from COIM 100 S.p.A. Milan, Italy) Curing agent (“DesmodurREQUEST FOR 5 EXAMINATION” from Bayer Material Science AG, Leverkusen,Germany) Methylethylketone 40 Melamine curing agent (“C6” from COIM 3S.p.A. Milan, Italy)

The polyurethane resin binder layer was partially dried at 80° C. At theend of the oven, the surface of the still tacky binder layer resin wassuperimposed and calendered onto a base fabric containing 65% polyesterand 35% cotton. After calendering the laminated fabric at 100° C. and apressure of 5 bars, the fabric was cooled and the temporary supportsheet was peeled off, yielding a fabric with the retroreflective printeddesign. This printed transferred image was cured at 150° C. in an ovenfor about 2 minutes to finish curing the polyurethane resin binderlayer, and yielding the retroreflective printed material.

EXAMPLE 2

A monolayer of glass microspheres having similar characteristics asthose disclosed in Example 1 was deposited on a temporary support sheetcomprising a coating film of low-density polyethylene film of 50 micronthickness supported by a backing sheet of 40 micron polyester film. Thecomposite of the temporary support sheet and microspheres was thenheated for between 2 and 4 minutes at between 150° C. and 160° C., whichyielded a penetration of the microspheres into the polyethylene film ofabout 40% of their diameter, with little or no space betweenmicrospheres. The exposed surface of the microspheres was then coatedwith a dielectric mirror layer, and the subsequent steps of the processwere the equivalent to those disclosed in Example 1.

EXAMPLE 3

A monolayer of glass microspheres having diameters between 40 and 100microns was produced by cascading the microspheres onto a thick releasepaper covered with an acrylic auto-adhesive film as described in Example2 of U.S. Pat. No. 4,075,049 to Wood. A priming layer comprising a resinof a water polyether polyurethane dispersion according to formulation 3was doctor-knife coated on the composite of the temporary support sheetand microspheres. Formulation 3 Ingredients Parts by Weight Polyurethanewater based resin (“Idrocap 100 930” from Icap-sira Chemicals andPolymers S.p.A., Milan, Italy) Curing agent (“Icaplink X3” Icap-sira 5Chemicals and Polymers S.p.A., Milan, Italy) water 40 thickening agent(“Idrocap 200” from a.r. Icap-sira Chemicals and Polymers S.p.A)

The amount of wet priming layer resin was about 10 g/m² and was adjustedwith the doctor-knife profile, resin dilution and viscosity. The amountof dried film was about 3 g/m². The priming layer resin was partiallycured at 110° C. At the end of the oven as disclosed with respect toFIG. 2, the product was fed into the calender, heated to 130° C., andlaminated with a transfer medium with the printed design comprising apolypropylene printed film (Decotrans™) having the design shown in FIG.5. The contact time was about 10 seconds. Then, the polypropyleneportion of the transfer medium without the printed design and theprinted transferred image were separated. The resulting printedtransferred image was further processed according to whether itcomprised a light reflecting material layer, in this case a vaporcoating of a metal such as an aluminum light reflecting material. Whenthe printed transferred image comprised the light reflecting materiallayer, the subsequent steps of the process were the same as disclosed inExample 1. When the composite did not comprise a light reflectingmaterial layer, the subsequent steps of the process comprised applying apolyurethane binder layer by knife coating, and then applying a textileto the binder layer.

The aesthetic printing effect without the light reflecting materiallayer was very regular but the average initial reflectivity was between8 and 15 cd/(luxm). This average initial reflectivity was low for use inconnection with retroreflecting garments for high risk professions, butwas suitable for use in connection with retroreflecting fashion fabric.The light reflecting material layer of the product with the lightreflecting material layer favorably affected the design colors and thereflectivity was greater than 50 cd/(luxm), making the product suitablefor use in connection with high risk professions.

EXAMPLE 4

A monolayer of glass microspheres having diameters between 40 and 100microns was produced by cascading the microspheres onto a thick releasepaper covered with an acrylic auto-adhesive film as described in Example2 of U.S. Pat. No. 4,075,049 to Wood. A dielectric mirror layer was thenapplied to the exposed microsphere surface of the composite of atemporary support sheet and microspheres. Next, a transfer print processwas made using a commercial transfer medium with a printed design withsublimate pigments from Transfertex GmbH & Co. The transfer temperaturewas about 185° C., however, the heated roll was in contact with the backof the transfer medium, and therefore, the real temperature of themicrosphere layer of the composite was higher than the real temperatureof the transfer medium, but sufficient for obtaining a good yield ofpigment sublimation onto the exposed surface of the microspheres. Next,a metallized light reflecting material layer was applied to the printedtransferred image using formulation 2 with a doctor-knife coatingmachine. Next, a polyurethane resin binder layer was applied and waspartially dried at 80° C. At the end of the oven, the surface of thestill tacky binder layer resin was superimposed and calendered onto abase fabric containing 65% polyester and 35% cotton. After calenderingthe laminated base fabric at 100° C. and a pressure of 5 bars, thefabric was cooled and the temporary support sheet was peeled off. Then,retroreflective printed fabric was cured at 150° C. in an oven for about2 minutes to finish curing the binder layer.

Although the present invention has been discussed in considerable detailwith reference to certain preferred embodiments, other embodiments arepossible. Therefore, the scope of the appended claims should not belimited to the description of preferred embodiments contained in thisdisclosure. All references cited herein are incorporated by reference intheir entirety.

1. A process for manufacturing retroreflective printed material, theprocess comprising: a) providing a composite comprising a temporarysupport sheet with a layer of microspheres partially embedded in thetemporary support sheet such that the surfaces of the microspheres arepartially exposed; b) applying a reflecting layer on the microspheres;c) applying a priming layer either on the partially exposed surfaces ofthe microspheres or on the reflecting layer; d) transferring a printeddesign layer from a transfer medium with the printed design on theprimer layer and separating the transfer medium without the printeddesign from the printed design layer; and e) applying a binder layer onthe printed design layer; f) applying a base fabric on the binder layerand separating the temporary support sheet from the layer ofmicrospheres, thereby creating the retroreflective printed material;where the reflecting layer is either applied on the microsphere surfaceof the composite between the priming layer and the microsphere surfaceof the composite, or is applied on the printed design layer between theprinted design layer and the binder layer.
 2. The process of claim 1,where the microspheres are transparent glass microspheres.
 3. Theprocess of claim 1, where the microspheres have a diameter, and wherethe microspheres are partially embedded in the temporary support sheetto a depth ranging between 40% and 50% of the microsphere diameter. 4.The process of claim 1, where the temporary support sheet comprises acoating film and a backing sheet.
 5. The process of claim 4, where thecoating film is selected from the group consisting of a polymericcoating film, polyethylene, polypropylene, a low-density polyethylenethermo-adhesive film and an acrylic auto-adhesive film.
 6. The processof claim 4, where the backing sheet is selected from the groupconsisting of kraft paper and polyester film.
 7. The process of claim 1,where providing a composite comprises placing the microspheres on thetemporary support sheet by a process selected from the group consistingof printing, cascading, transferring and screening.
 8. The process ofclaim 1, where the reflecting layer is a dielectric mirror layer appliedon the microsphere surface of the composite, and where the priming layeris applied on the dielectric mirror layer.
 9. The process of claim 1,where the reflecting layer is a light reflecting material layer appliedon the printed design layer, and where the binder layer is applied onthe light reflecting material layer.
 10. The process of claim 9, wherethe light reflecting material layer is a vapor coating of a metal orthin reflective aluminum film layer applied by vacuum deposition. 11.The process of claim 1, where the priming layer is selected from thegroup consisting of a thin layer of transparent thermo-adhesivebicomponent polyurethane resin and a resin of a water polyetherpolyurethane dispersion.
 12. The process of claim 1, where the printeddesign layer from a transfer medium with the printed design comprises aplurality of colors.
 13. The process of claim 1, where the transfermedium with the printed design comprises a design with sublimatepigments.
 14. The process of claim 13, where transferring a printeddesign comprises thermo-transferring at a temperature between 180° C.and 220° C.
 15. The process of claim 1, where the transfer medium withthe printed design comprises a design printed on a polymer film.
 16. Theprocess of claim 15, where transferring a printed design comprisesthermo-transferring at a temperature between 100° C. and 120° C.
 17. Theprocess of claim 1, where the binder layer is selected from the groupconsisting of a bicomponent polyurethane resin and a thin layer of ahot-melt adhesive.
 18. A retroreflective printed material made accordingto claim
 1. 19. An article of clothing, sportswear or footwearcomprising the retroreflective printed material of claim
 18. 20. Aretroreflective printed material comprising: a) a microspheres layer; b)a priming layer on the microsphere layer; c) a printed design layer onthe primer layer; d) a binder layer on the printed design layer; e) abase fabric on the binder layer; and f) a reflecting layer; where thereflecting layer is either between the microsphere layer and the priminglayer, or is between the printed design layer and the binder layer. 21.The retroreflective printed material of claim 20, where the microspheresare transparent glass microspheres.
 22. The retroreflective printedmaterial of claim 20, where the reflecting layer is a dielectric mirrorlayer.
 23. The retroreflective printed material of claim 20, where thereflecting layer is a vapor coating of a metal or thin reflectivealuminum film layer.
 24. The retroreflective printed material of claim20, where the priming layer is selected from the group consisting of athin layer of transparent thermo-adhesive bicomponent polyurethane resinand a resin of a water polyether polyurethane dispersion.
 25. Theretroreflective printed material of claim 20, where the printed designlayer comprises a plurality of colors.
 26. The retroreflective printedmaterial of claim 20, where the binder layer is selected from the groupconsisting of a bicomponent polyurethane resin and a thin layer of ahot-melt adhesive.